Conventionally, a large number of games where a plurality of objects appear in a three-dimensional space have been available. In such a game, where to set a virtual camera, particularly, which area on the game space is set as a display area, is an important issue. When a plurality of objects are all important objects in the game, the display area is set so that all of these objects can be displayed inside of the display area.
In view of the above, a game system has been devised in which a display area in a game space can be changed so that a plurality of objects can be included in the display area. In such a game system, two frames, an inner frame and an outer frame, are set on a screen. Using these frames, image zoom-up or zoom-down is performed. Here, such a game system is specifically described below by taking a soccer game as an example. When all athlete characters (objects) are present inside of the inner frame, the image is zoomed up (the display area is reduced). When one of the athlete characters goes outside of the outer frame, the image is zoomed down (the display area is enlarged). With this, a plurality of objects (for example, a soccer ball and the athlete characters) can be included in the display area.
In the above exemplary game system, a fixation point on the display area (the fixation point is assumed herein to be the center point of the display area, that is, a point displayed at the center of the screen) is set fixedly at a single specific object. Specifically, since the above game system is for a soccer game, the fixation point is set at a soccer ball object. That is, the display area is determined so that the soccer ball is always displayed near the center of the screen.
However, depending on the game contents, the scheme of setting a fixation point fixedly at a single object may not be appropriate. For example, the scheme may not be appropriate for multiplay-type games where characters are operated by a plurality of players, that is, games where objects to which a plurality of players would pay attention are present on a single screen. In such games, if the fixation point is set fixedly at one particular object, that object is displayed on the center of the screen, and therefore the state of the object and its surroundings is displayed so as to be easy to view. However, other objects and their surroundings are not necessarily displayed so as to be easy to view.
For example, in multiplay-type games, each player pays most attention to a player character operated by that player. That is, each player pays attention to each different character. However, in the conventional scheme, the fixation point is set fixedly at only one of the characters, and that character is always displayed at the center of the screen. Such a display is easy to view for a player who pays most attention to the character displayed on the center of the screen. For other players, however, such a display is not easy to view and might be unfair insofar as viewability of the screen. As such, the scheme of setting the fixation point at one specific point in the game space is not necessarily appropriate when a plurality of objects receiving attention are present because viewability of the object at the fixation point and viewability of other objects are completely different from each other.
The illustrative embodiments provide a game system that allows a plurality of objects to be displayed so as to be easy to view.
The illustrative embodiments adopt the following structure to achieve the object mentioned above. Note that reference characters and numerals in parentheses below are used for exemplary purposes only for the sake of better understanding of the present invention, and do not restrict the scope of the present invention.
A first aspect of the illustrative embodiments is directed to a game system (1) for causing a three-dimensional virtual game space (game space 71) to be displayed on a display device (television 2) in a direction of a predetermined line of sight (73). The three-dimensional virtual game space has a plurality of objects appearing therein. In this game system, at least two of the plurality of objects are set as selected objects (first to third player characters 81 through 83 and first enemy character 84). Also, the game system includes line-of-sight direction setting means (CPU 31 executing step S1; only step number is hereinafter referred); frame-setting-plane setting means (S401); frame-coordinate-value calculating means (S402); frame setting means (S404 through S419); and display control means (S6 and S7). The line-of-sight direction setting means sets the direction of the line of sight. The frame-setting-plane setting means sets a frame setting plane (76) in the three-dimensional game space. The frame-coordinate-value calculating means calculates a frame coordinate value. The frame coordinate value indicates, for each of the selected objects, a point of intersection of the frame setting plane and a straight line passing through the selected object in the three-dimensional game space and extending along the line of sight set by the line-of-sight direction setting means. The frame setting means virtually sets a frame (first frame 77 or second frame 78) on the frame setting plane, the frame including every position indicated by the frame coordinate value of each of the selected objects. The display control means determines vertices of a view volume based on vertices of the frame set by the frame setting means and causes the game space to be displayed on the display device.
Typically, the display control means determines points on a straight line passing through the vertices of the frame set by the frame setting means and extending along the line of sight set by the line-of-sight direction setting means as the vertices of the view volume.
Also, the frame-setting-plane setting means typically sets a plane perpendicular to the direction of the line of sight set by the line-of-sight direction setting means as the frame setting plane.
A second aspect of the illustrative embodiments is directed to a game system for causing a three-dimensional virtual game space to be displayed on a display device in a direction of a predetermined line of sight. The three-dimensional virtual game space has a plurality of objects appearing therein. In this game system, at least two of the plurality of objects are set as selected objects. The game system includes: viewing point position setting means; frame-setting-plane setting means; frame-coordinate-value calculating means; frame setting means; and display control means. The viewing point position setting means sets a position of a viewing point. The frame-setting-plane setting means sets a frame setting plane in the three-dimensional game space. The frame-coordinate-value calculating means calculates for each of the selected objects, a frame coordinate value indicative of a point of intersection of the frame setting plane and a straight line connecting the selected object in the three-dimensional game space and the position of the viewing point set by the viewing point position setting means. The frame setting means virtually sets a frame on the frame setting plane, the frame including every position indicated by the frame coordinate value of each of the selected objects. The display control means determines vertices of a view volume based on vertices of the frame set by the frame setting means and causes the game space to be displayed on the display device.
Typically, the display control means determines points on a straight line passing through the vertices of the frame set by the frame setting means and extending toward a direction of the viewing point as the vertices of the view volume.
The game system may further include frame expanding means (S404 through S411). The frame expanding means expands the frame set by the frame setting means by a predetermined width upward, downward, rightward, and leftward on the frame setting plane. At this time, the display control means determines the vertices of the view volume based on the vertices of the frame expanded by the frame expanding means.
When a screen area provided on the display device for displaying the three-dimensional game space is set to have a shape of a rectangle having a predetermined aspect ratio, the game system may further include aspect ratio correcting means (S507 through S509). The aspect ratio correcting means increases either one of a height or a width of the frame so that an aspect ratio of the frame set by the frame setting means is equal to the predetermined aspect ratio. At this time, the display control means determines the vertices of the view volume based on the vertices of the frame corrected by the aspect ratio correcting means.
Furthermore, the aspect ratio correcting means corrects the frame a center of the frame is not changed before and after correction.
Still further, the game system may be used by a plurality of players for playing a game. At this time, the selected objects at least include a plurality of player characters operated by the plurality of players.
The illustrative embodiments may be provided in a form of a game program to be executed by a computer of a game system or in a form of a storage medium having stored therein the game program. That is, the functions of the above-described game system may be provided by the game program to the game system.
According to the illustrative embodiments, the display area is determined based on the frame virtually set in the three-dimensional game space. As such, by determining the display area (view volume) without using a fixation point, it is possible to prevent a situation in which only a specific single object is displayed at the center of the screen. Therefore, even the game has a plurality of objects to get attention, each object can be displayed similarly. That is, a plurality of objects can be displayed so as to be easy to view.
Also, the display control means determines points on the straight lines each passing through the relevant vertex of the set frame as the vertices of the view volume. With this, the view volume can be easily determined based on the direction of the line of sight.
Furthermore, a plane perpendicular to the direction of the line of sight is set as the frame setting plane. Therefore, the positional relation between the selected objects and the frame on the frame setting plane is identical to that between the selected objects and the display screen on a game image actually displayed. Therefore, the frame can be set with the actual display state being accurately reflected thereon, thereby making it easier to set the frame.
Still further, points on the straight lines connecting the viewing point and the vertices of the frame set by the frame setting means are determined as the vertices of the view volume. With this, the view volume can be easily determined based on the viewing point.
Still further, the frame enlarging means can prevent any selected object from being displayed at the edge of the screen. Therefore, the plurality of selected objects can be displayed so as to be easier to view.
Still further, the size of the display area is changed only when both of the height and the width of the frame are changed by the aspect ratio correcting means. That is, when only either one of the height and the width of the first frame is changed, the size of the display area is not changed. Therefore, frequent changes in size of the display area can be further prevented, thereby improving viewability of the screen. Also, by correcting the aspect ratio, the game image can be prevented from being extended in the height or width direction. The shape of the near clipping plane and the shape of the far clipping plane of the view volume always have a shape similar to the shape of the screen area on which the game image of a game world is to be displayed. Therefore, the game image can be displayed so as to be always easy to view. Furthermore, when the frame is corrected so that the frame deformed by the frame deforming means is positioned at a center of a frame having the corrected aspect ratio, information that would be required for the player(s), that is, the selected objects, are displayed near the center of the screen. Therefore, the game screen can be displayed so as to be easier to view.
Still further, when the selected objects include at least a plurality of player characters operated by a plurality of players, all player characters can be displayed so as to be easy to view. Therefore, a display that is easy to view can be offered to all players.
These and other aspects illustrative embodiments will become more apparent from the following detailed description of the illustrative embodiments when taken in conjunction with the accompanying drawings.